1. Field of the Invention
The invention relates to a phase change memory device, and more particularly relates to a phase change memory material of a phase change memory device.
2. Description of the Related Art
Phase change memory has many advantages, such as fast speed, lower power consumption, high capacity, robust endurance, easy embeddability in logic IC, and lower cost, so that it can serve as a stand-alone or embedded memory device with high integrity. Due to the described advantages, phase change memory has been considered the most promising candidate for the next-generation nonvolatile semiconductor memory which may replace the commercialized volatile memory, such as SRAM or DRAM, and non-volatile memory, such as flash.
Chalcogenide is widely used in phase change memory devices. The chemical element of group VI, such as S, Se or Te, is the major material of Chalcogenide and is combined with elements of group IV or V and some dopants for use in phase change memory devices. Ge2Sb2Te5 is the most popular material used in phase change memory devices because it can provide a binary state switching with a fast and reversible phase transition between an amorphous phase (with extremely high electrical resistivity) and a crystalline phase (with very low electrical resistivity). Ge2Sb2Te5, however, still has deficiencies which include low crystallization temperature, low electrical resistivity at crystalline state while high melting temperature, containing major amount of Te which is highly volatile and toxic to easily contaminate the processing chamber and its environment, among others. A novel phase change material is required to promote performance of phase change memory devices, as well as to lessen the burden to environment.